package lumis.util.security;

/**
 * Methods for encoding and decoding using Base64 algorithm.
 * @version $Revision: 11180 $ $Date: 2009-12-04 18:13:02 -0200 (Fri, 04 Dec 2009) $
 * @since 4.0.0
 * @deprecated Since 5.5.0 this class is no longer maintained and
 * may be removed in a future version. It is recommended to use another 
 * implementation, such as {@link org.apache.commons.codec.binary.Base64}.
 */
@Deprecated
public class Base64
{
	/**
	 * This array is a lookup table that translates 6-bit positive integer
	 * index values into their "Base64 Alphabet" equivalents as specified 
	 * in Table 1 of RFC 2045.
	 */
	private static final char intToBase64[] = { 'A', 'B', 'C', 'D', 'E', 'F',
			'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S',
			'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
			'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's',
			't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5',
			'6', '7', '8', '9', '+', '/' };

	/**
	 * This array is a lookup table that translates unicode characters
	 * drawn from the "Base64 Alphabet" (as specified in Table 1 of RFC 2045)
	 * into their 6-bit positive integer equivalents.  Characters that
	 * are not in the Base64 alphabet but fall within the bounds of the
	 * array are translated to -1.
	 */
	private static final byte base64ToInt[] = { -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1,
			-1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
			13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1,
			-1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
			41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 };

	public static String encode(byte[] a)
	{
		int aLen = a.length;
		int numFullGroups = aLen / 3;
		int numBytesInPartialGroup = aLen - 3 * numFullGroups;
		int resultLen = 4 * ((aLen + 2) / 3);
		StringBuilder result = new StringBuilder(resultLen);

		// Translate all full groups from byte array elements to Base64
		int inCursor = 0;
		for (int i = 0; i < numFullGroups; i++)
		{
			int byte0 = a[inCursor++] & 0xff;
			int byte1 = a[inCursor++] & 0xff;
			int byte2 = a[inCursor++] & 0xff;
			result.append(intToBase64[byte0 >> 2]);
			result.append(intToBase64[(byte0 << 4) & 0x3f | (byte1 >> 4)]);
			result.append(intToBase64[(byte1 << 2) & 0x3f | (byte2 >> 6)]);
			result.append(intToBase64[byte2 & 0x3f]);
		}

		// Translate partial group if present
		if (numBytesInPartialGroup != 0)
		{
			int byte0 = a[inCursor++] & 0xff;
			result.append(intToBase64[byte0 >> 2]);
			if (numBytesInPartialGroup == 1)
			{
				result.append(intToBase64[(byte0 << 4) & 0x3f]);
				result.append("==");
			}
			else
			{
				int byte1 = a[inCursor++] & 0xff;
				result.append(intToBase64[(byte0 << 4) & 0x3f | (byte1 >> 4)]);
				result.append(intToBase64[(byte1 << 2) & 0x3f]);
				result.append('=');
			}
		}

		return result.toString();
	}

	public static byte[] decode(String s)
	{
		int sLen = s.length();
		int numGroups = sLen / 4;
		if (4 * numGroups != sLen)
			throw new IllegalArgumentException(
					"String length must be a multiple of four.");
		int missingBytesInLastGroup = 0;
		int numFullGroups = numGroups;
		if (sLen != 0)
		{
			if (s.charAt(sLen - 1) == '=')
			{
				missingBytesInLastGroup++;
				numFullGroups--;
			}
			if (s.charAt(sLen - 2) == '=')
				missingBytesInLastGroup++;
		}
		byte[] result = new byte[3 * numGroups - missingBytesInLastGroup];

		// Translate all full groups from base64 to byte array elements
		int inCursor = 0, outCursor = 0;
		for (int i = 0; i < numFullGroups; i++)
		{
			int ch0 = base64toInt(s.charAt(inCursor++));
			int ch1 = base64toInt(s.charAt(inCursor++));
			int ch2 = base64toInt(s.charAt(inCursor++));
			int ch3 = base64toInt(s.charAt(inCursor++));
			result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4));
			result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2));
			result[outCursor++] = (byte) ((ch2 << 6) | ch3);
		}

		// Translate partial group, if present
		if (missingBytesInLastGroup != 0)
		{
			int ch0 = base64toInt(s.charAt(inCursor++));
			int ch1 = base64toInt(s.charAt(inCursor++));
			result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4));

			if (missingBytesInLastGroup == 1)
			{
				int ch2 = base64toInt(s.charAt(inCursor++));
				result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2));
			}
		}

		return result;
	}

	/**
	 * Translates the specified character, which is assumed to be in the
	 * "Base 64 Alphabet" into its equivalent 6-bit positive integer.
	 *
	 * @throw IllegalArgumentException or ArrayOutOfBoundsException if
	 *        c is not in the Base64 Alphabet.
	 */
	private static int base64toInt(char c)
	{
		int result = base64ToInt[c];
		if (result < 0)
			throw new IllegalArgumentException("Illegal character " + c);
		return result;
	}

}
